NTSB LAX99LA202 — 1999-05-29 · LAKE BERRYESSA, California, United States

Aircraft involved

N20869 Beech D-45 None

Probable cause & findings

Loss of engine power due to a loose adjustment nut on the engine driven fuel pump that allowed for a decrease in fuel flow and fuel pressure, and the subsequent failure of the electric fuel boost pump due to loose bearings decreasing fuel flow and fuel pressure to sustain engine power.

Factual narrative

HISTORY OF FLIGHT

On May 29, 1999, at 1400 hours Pacific daylight time, a Beech D-45, N20869, experienced a loss of engine power during cruise near Lake Berryessa, California. The airplane subsequently ditched into Lake Berryessa while attempting to return to the airport. The airplane, operated by the Travis Air Force Base (AFB) Aero Club under 14 CFR Part 91, sustained substantial damage. The airline transport pilot, an employee at the Aero Club, and a non-pilot rated passenger were not injured. Visual meteorological conditions existed for the local area personal flight and no flight plan was filed. The flight originated from Travis AFB, Fairfield, California, at 1330. An inspector from the Federal Aviation Administration (FAA) interviewed the pilot. The pilot stated that the purpose of the flight was to view the lake and the surrounding area. He further indicated that he was not conducting aerobatic maneuvers, and that the flight had been approximately 30 minutes when he noted a loss of fuel pressure and a corresponding rough running engine. He stated that he believed he had lost the engine driven fuel pump and switched the electric boost pump on. The pilot reported that the fuel pressure came back on-line and the engine began to run "normally." He turned the airplane back to the airport to make a precautionary landing when he noted that the fuel pressure gage needle began to move sporadically and the engine began to run rough and subsequently lost power. He stated that he was at 2,000 feet when he "adjusted the mixture settings, throttle settings, and unsuccessfully cycled the electric fuel pump." According to the Navy's NATOPS Flight Manual (page 1-12) that the Aero club uses for this airplane, "the fuel control is not equipped with an automatic mixture control. For altitude compensation leave the mixture in the Full Rich position during all flight operations." The emergency checklist indicates that the mixture control should be in the rich position when attempting to restart the engine. If the engine does not start the mixture control should be placed in the idle cutoff position. No discrepancies were noted with the flight prior to the loss of engine power. The pilot further stated that he and his passenger exited the airplane with no discrepancies and were picked up by a pleasure boat.

TESTS AND RESEARCH

An FAA inspector examined the airplane at the United States Air Force storage facility at Travis AFB. According to the airplane logbook, the airplane had gone in for repair work and had been returned to service in an airworthy condition. The inspector stated that it had been flown for approximately 46 hours after the repair work had been completed. He noted that the airplane had been refueled with 50 gallons of fuel prior to the accident flight, and had flown approximately 30 minutes. He inspected the fuel system and noted that the fuel lines from the firewall to the engine were clear of obstructions. He also noted that the fuel line of the fuel control unit to the fuel distributor was clear of obstructions. The engine oil screen appeared free of foreign material and there were no discrepancies noted with the oil. The inspector removed the engine driven fuel pump and the electric boost pump for inspection. A manual test was completed on the electric boost pump with a pressure metering gage (0-50 psi), an air drill (800 - 1,000 rpm), and fuel. During the testing of the electric boost pump, the pump shorted out; however, prior to the short no output was observed from the pump. Both pumps were sent to the Safety Board investigator for further testing. The inspections and tear down examinations of the engine driven fuel pump and electric boost pump were conducted at Ontic Engineering in North Hollywood, California, on July 20, 1999, by a Safety Board investigator. The examination of the engine driven fuel pump revealed that it was overhauled in January 1979. The adjusting nut of the engine driven fuel pump was found loose. The adjusting nut is used to decrease or increase the amount of fuel flow; when the adjusting nut is turned counterclockwise it will decrease the fuel flow, if the adjusting nut is turned clockwise the fuel flow increases. The first functional check on the engine driven fuel pump was in the as-received condition, with the adjusting nut loose. The results were consistently low, but fuel flow was observed from the pump. The adjusting nut was readjusted to overhaul specifications for the second functional check, and fell within overhaul specifications. During the teardown of the electric boost pump it was noted that the bearings were loose, allowing the pump vanes to rub up against the throat of the pump reducing fuel pressure and fuel flow to the engine. The spring in the bearings was noted to be in good condition; the brushes were moveable and in good condition. Water was present in the electric boost pump, and the pump evidenced rust and corrosion that was attributed to the water immersion. No further discrepancies were noted. The airplane was retrieved by the U.S. Air Force. The purpose of the flight was to fly over the lake with the intent of viewing the lake and surrounding area. The lake is 10 miles from the airport. Approximately 30 minutes into the flight the pilot noted a loss of fuel pressure followed by a rough running engine. He believed that the engine driven fuel pump had failed. He engaged the electric boost pump and the fuel pressure came back on-line and engine ran normally. The pilot decided to return to the airport to make a precautionary landing. He again noted that the fuel pressure gage needle began to move sporadically and the engine began to run rough and subsequently lost power. He made an unsuccessful attempt to restart the engine utilizing the in-flight engine failure checklist and subsequently ditched the airplane in the lake. No discrepancies were noted with the flight prior to the loss of engine power. The fuel system was inspected with no foreign debris found. A functional check was performed on the electric boost pump and no fuel flow output was observed; however, during the test the pump shorted out. Both the engine driven fuel pump and electric boost pump were sent out for further tests. Two functional checks were conducted on the engine driven fuel pump. An adjusting nut on the engine driven fuel pump allows for an increase or decrease in fuel flow. The first test was completed in the as-received condition with the adjusting nut loose. The results were consistently low, but fuel flow output was observed from the pump. The adjusting nut was then readjusted to overhaul specifications for the second functional check. The check revealed that the fuel flow was within overhaul specifications. During the teardown of the electric boost pump, it was noted that the bearings were loose allowing the pump vanes to rub up against the throat of the pump, decreasing fuel flowing through the fuel system. Source: NTSB Aviation Accident Database (Pre-2008 Archive) Retrieved: 2026-02-12

Verbatim from NTSB's published report. Source file NTSB_1999_LAX99LA202.txt. Findings + structured fields enriched from FAA avall.mdb. Full investigation docket on data.ntsb.gov ↗.

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